From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Pascal J. Bourguignon" Newsgroups: gmane.emacs.help Subject: Re: Why is booleanp defined this way? Date: Sat, 18 Apr 2015 05:50:21 +0200 Organization: Informatimago Message-ID: <87bnimm6wy.fsf@kuiper.lan.informatimago.com> References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1429329622 21457 80.91.229.3 (18 Apr 2015 04:00:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 18 Apr 2015 04:00:22 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sat Apr 18 06:00:18 2015 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YjJvW-0005rr-LA for geh-help-gnu-emacs@m.gmane.org; Sat, 18 Apr 2015 06:00:18 +0200 Original-Received: from localhost ([::1]:44424 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YjJvV-0005gC-IA for geh-help-gnu-emacs@m.gmane.org; Sat, 18 Apr 2015 00:00:17 -0400 Original-Path: usenet.stanford.edu!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 27 Original-X-Trace: individual.net /KRCLTMcYZuW16A/5SOf7QAbAW80VHeEryvAxtRXqhdN1raOd8 Cancel-Lock: sha1:NmM2NDA5Y2Y1NjRjM2MwMzJjNTliYmE0OGNiNDY0NWE4NGE2ZGI3ZQ== sha1:jhSbzPTm7ScGz88RpEVsst4MHJA= Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwAQMAAABtzGvEAAAABlBMVEUAAAD///+l2Z/dAAAA oElEQVR4nK3OsRHCMAwF0O8YQufUNIQRGIAja9CxSA55AxZgFO4coMgYrEDDQZWPIlNAjwq9 033pbOBPtbXuB6PKNBn5gZkhGa86Z4x2wE67O+06WxGD/HCOGR0deY3f9Ijwwt7rNGNf6Oac l/GuZTF1wFGKiYYHKSFAkjIo1b6sCYS1sVmFhhhahKQssRjRT90ITWUk6vvK3RsPGs+M1RuR mV+hO/VvFAAAAABJRU5ErkJggg== X-Accept-Language: fr, es, en User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Original-Xref: usenet.stanford.edu gnu.emacs.help:211520 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:103802 Archived-At: Rusi writes: > Elisp does not have a proper boolean type; unlike say symbols with > symbolp, strings with stringp, numberp -- some union of numeric types etc. > However programmers need boolean in their ontology even if (and even more if) > the language does not support it. Well, if you go this way, elisp doesn't have proper types at all!!! deftype, typep, subtypep are all defined in cl.el and as such, "frowned upon" by the PTB. > I'd say booleanp is a hesitant step towards supporting boolean in the ontology > without supporting it in the language. Let's go boldly where no other elispers has ever gone: (deftype boolean () `(member t nil)) (defun booleanp (x) (typep x 'boolean)) -- __Pascal Bourguignon__ http://www.informatimago.com/ “The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment.” -- Carl Bass CEO Autodesk